This invention relates to gene delivery. More particularly, this invention relates to compositions of matter and methods of use and making thereof for gene delivery wherein the compositions of matter comprise amphiphilic lipoproteins configured for binding nucleic acids.
Progress in the area of gene delivery has been tremendous in the last several years, yet in clinical settings the dream of a successful therapy based on nucleic acids remains a frustrating riddle. Gene delivery vectors have been largely put into either of two categories, viral or non-viral, and most of the published reports have focused on circumventing the deficiencies inherent in both types of vectors. Factors such as toxicity, permanently altering the host genome through recombination events with viral vectors, and poorly optimized delivery capabilities with non-viral vectors demand application of concepts that have clinical relevance in terms of safety, efficacy, and patient compliance. However, by now its clear that feasibility of a single vector serving as a universal gene carrier for all disease targets is remote and impractical.
In cancer immunotherapy, for example, the use of cytokines such as interleukin-12, which is a proven anti-proliferative cytokine in confinement and inhibition of tumor progression and metastasis in several types of cancers in vivo, is of great interest. Although cytokine gene therapy has been attempted with a variety of viral vectors, such as adenovirus, retrovirus, adeno-associated viruses, and lentiviruses, there is still a growing need to optimize non-viral gene carriers with unprecedented safety and efficacy profiles. Among existing non-viral gene carriers polyethyleneimine, and lipid-protamine-DNA (LPD) lipoplexes have had some success in terms of cytokine gene transfer efficiency, however the issues related to carrier-associated toxicities are poorly understood. Cationic lipids are water insoluble and require the formation of liposomes using a colipid, such as dioleyl phophatidylethanolamine (DOPE) or cholesterol in presence of organic solvents, which involves multiple steps. Although their gene transfer applications have been under investigation since 1987, the exact mechanism elucidating their structure-function relationship has not been completely revealed. It is believed that lipid anchors, such as steroids and fatty acid chains, serve to provide amphiphilic character to these carriers, which would orient the head group surface charge more favorably, and also take part in hydrophobic interactions with plasma and organelle membranes. Lipid anchors can also interact specifically with various membrane receptors for enhanced cellular uptake and lipid-mediated transduction. Polyethyleneimine and Starburst™ dendrimers, due to their high transfection efficiency, have received a lot of attention and remain, by far, the most effective cationic polymers for transfection created to date. The functioning of these polymers has been attributed to the so-called proton sponge effect due to secondary and tertiary amines present in these polymers, which supposedly leads to disruption inside endosomes and end-lysosomes by osmotic swelling. Gene carriers that would combine the concepts of water solubility, amphiphilic nature, lipid mediated membrane interactions, endosomal buffering, and nuclear targeting would be an exciting option for plasmid based gene therapy.
Peptide based gene delivery systems are least investigated, and their applications in delivering cytokine genes are virtually unexplored. Several different types of peptides that possess endosomolytic, fusogenic, or membrane permeabilizing properties derived from various viruses, such as vesicular stomatitis virus glycoprotein (VSVG) and influenza virus hemaglutinin, have been used either alone or in combination with liposomes and polymers. Co-polymers of lysine and histidine have also been shown to efficiently deliver genes inside cells, and this property has been attributed to the imidazole ring of the histidine side chain, which behaves as an endosomal rupturing agent.
While prior compositions and methods for delivering peptides are known and are generally suitable for their limited purposes, they possess certain inherent deficiencies that detract from their overall utility. For example, polyethyleneimine is effective only in high molecular weight (>10,000 M.W.) formulations, but such high molecular weight compositions can be toxic, elicit immune responses, are non-biodegradable, are not site specific, and condense plasmid DNA too tightly. Cationic lipids can be toxic at therapeutic doses, elicit immune responses, require several steps to synthesize and involve the use of organic solvents, are water insoluble, offer little inherent endosomal buffering, and are not site specific. Current peptide-based gene carriers may be toxic at therapeutic doses, elicit immune responses, often require cationic lipids for effectiveness, frequently are subject to aggregation, and exhibit poor water solubility due to hydrophobic amino acid residues.
In view of the foregoing, it will be appreciated that providing compositions and methods for delivering peptides, especially cytokines, would be a significant advancement in the art.